Electric toothbrush

ABSTRACT

In one aspect, the present invention is directed to an electric toothbrush. The toothbrush includes a housing, an electric motor, a first transmission and a second transmission. The electric motor is connected to the housing has a motor output member for rotation about a motor output axis. The first transmission is connected to the housing, and converts rotational movement from the motor output member into rotational reciprocating movement at a first average angular speed. The second transmission is linked to the first transmission, and converts rotational reciprocating movement from the first transmission into rotational reciprocating movement at a second average angular speed about a second transmission output axis that is parallel to the motor output axis. The second transmission drives an output member to reciprocate at the second average angular speed about the second transmission output axis. A brush head is removably connectable to the output member.

[0001] This application is a continuation of U.S. application Ser. No.09/892,861 filed Jun. 28, 2001, the entirety of which is herebyincorporated by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to an electric toothbrush.

BACKGROUND OF THE INVENTION

[0003] Electric toothbrushes utilize an electric motor to drive a brushhead to provide a brushing action for cleaning teeth. One suchtoothbrush is disclosed by Sham in U.S. Pat. No. 5,822.821. Shamdiscloses an electric toothbrush having a motor, which drives a drivengear. The driven gear drives a crank member. The crank member, in turndrives a reciprocating rocker arm. The rocker arm, in turn, drives abrush head. The rate of rotation of the driven gear in the devicedetermines the frequency of reciprocation of the brush head, while thelength and shape of the crank member determine the angular sweep and theaverage angular speed of the brush head.

SUMMARY OF THE INVENTION

[0004] The present invention is directed to an electric toothbrush,comprising a housing, an electric motor, a first transmission and asecond transmission. The electric motor is linked to the housing, anddrives a motor output member for rotation about a motor output axis. Thefirst transmission is linked to the motor output member and convertsrotational movement from the motor output member into rotationalreciprocating movement at a first average angular speed and along afirst angular sweep. The second transmission is linked to the firsttransmission and converts rotational reciprocating movement from thefirst transmission into rotational reciprocating movement at a secondaverage angular speed about a second transmission output axis that isparallel to the first axis, and along a second angular sweep. The secondtransmission drives an output member to reciprocate at the secondaverage angular speed about the second transmission output axis, andalong the second angular sweep. The second transmission can includefirst and second gear members. The first gear member can include asection of an internal gear connected to the first transmission. Thesecond gear member is drivenly connected to the first gear member andcomprises a spur gear. The output member can include a removablyattachable brush head.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The present invention will now be described by way of exampleonly with reference to the attached drawings in which:

[0006]FIG. 1 is a cutaway side elevation view of an electric toothbrushin accordance with a preferred embodiment of the present invention;

[0007]FIG. 2a is an exploded perspective view of a portion on theelectric toothbrush shown in FIG. 1;

[0008]FIG. 2b is another exploded perspective view of a portion on theelectric toothbrush shown in FIG. 1; and

[0009]FIG. 3 is a perspective view of the portion on the electrictoothbrush shown in FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

[0010] Reference is first made to FIG. 1, which illustrates an electrictoothbrush 10 in accordance with a first preferred embodiment of thepresent invention. Toothbrush 10 provides a reciprocating,back-and-forth brushing action, with a large angular sweep during eachstroke.

[0011] Toothbrush 10 comprises motor 12, a power source 14, a housing16, a drive mechanism 18 and an output member 20. Motor 12 drives drivemechanism 18 and, in turn, output member 20. Motor 12 can be anysuitable compact electric motor. Power source 14 is used to supply powerto motor 12. Power source 14 is preferably a battery, as shown in FIG.1, but may alternately be a connection to an external power source, suchas, for example, an electric wire and plug for connection to a standard120 VAC source. A control line 22 connects power source 14 to motor 12.Control line 22 schematically represents a suitable electricalconnection between power source 14 and motor 12. A switch 23 is includedon the housing, and connects to control line 22 to start and stop motor12.

[0012] Housing 16 surrounds motor 12, power source 14 and drivemechanism 18, and can provide a base for mounting the components.Housing 16 is made from a suitable, water impermeable plastic to preventwater from damaging the internal electrical components and to prevent auser from potential harm during use. Alternatively, housing 16 can bemade from other suitable, water impermeable materials, such as asuitable metal, or from a composite of materials such as metal andplastic.

[0013] Reference is now made to FIGS. 2a and 2 b, which illustrate drivemechanism 18. Motor 12 drives an output shaft 24, on which is mounted apinion gear 26. Output shaft 24 and pinion gear 26 rotate about a firstaxis 28, which is the motor output axis. Pinion gear 26 drives therotation of a first member 30.

[0014] First member 30 includes an internal gear 32 and rotates about asecond axis 34. At the forward end of internal gear 32 is a central disc36. Disc 36 has a first face 38 (see FIG. 2a) from which a central shaft40 extends. The distal end of shaft 40 rotates within a hole 42, for theembodiment illustrated, the casing of motor 12. Disc 36 has a secondface 44 from which a bearing portion 46 extends. Bearing portion 46 hasa bearing surface 48 and an end face 50, from which an orbiting member52 extends. Orbiting member 52 is positioned towards the outside edge ofend face 50, so that as first member 30 rotates about axis 34, orbitingmember 52 orbits about axis 34.

[0015] A second member 54 is attached to a square recess 56, for theembodiment illustrated, the casing of motor 12, and to bearing portion46 of first member 30. Second member 54 includes a bearing hoop 58 forsupporting the rotation of bearing portion 46 therein. Bearing portion46 and bearing hoop 58 have substantially the same width. Orbitingmember 52, which is mounted on bearing portion 46, extends past theforward face of bearing hoop 58.

[0016] A third member 60 includes a body 62. A first shaft portion 64extends rearwardly from body 62 and is received in a hole 66 in thesecond member 54 for rotation therein about a third axis 68. A secondshaft portion 70 extends forwardly from body 62. The third member 60includes a slotted arm 72, which extends radially from body 62. Arm 72defines a slot 74 that receives and engages orbiting member 52. Asorbiting member 52 orbits about axis 34, the orbiting motion causes arm72 to reciprocate rotationally about axis 68. In use, arm 72reciprocates through an angular sweep A₁ at an average angular speed W₁.

[0017] As arm 72 reciprocates, it will have a range of angular speeds,ranging from a speed of zero at the ends of the reciprocation to amaximum speed in the middle of the reciprocation. Since theinstantaneous speed of arm 72 varies depending on its position, theaverage angular speed is used for the purposes of this disclosure.

[0018] Extending forwardly from arm 72 is a gear member 76 which is asection of an internal gear. A fourth member 78 includes a receivinghole 80 for receiving shaft portion 70 so that shaft portion 70 canrotate therein. Fourth member 78 includes a bearing portion 82, in whichis mounted output member 20. Output member 20 rotates within bearingportion 82 about a fourth axis 86, and includes at its rear end a spurgear member 88 which is driven about axis 86, through an angular sweepA₂ at an average angular speed W₂ by gear member 76 on third member 60.Gear member 88 has a smaller radius than gear member 76. The averageangular speed W₂ and the angular sweep A₂ of gear member 88 are largerthan the average angular speed W₁ and the angular sweep A₁ of gearmember 76 in inverse proportion to the ratio of their radii. Thus, arelatively large angular sweep and a high rotational speed are achievedin output member 20 while keeping the angular sweep and the rotationalspeed relatively low in the arm 72. As shown in FIG. 1, the forwardportion of output member 20 protrudes through a hole in housing 16, andincludes a square end portion 90, for the mounting of a brush headmember 92 thereon.

[0019] Referring back to FIGS. 2a and 2 b, brush head member 92 includesa mounting portion 94 for receiving end portion 90 of output member 20.Head member 92 includes a brush head 96 that comprises an arrangement ofbristles 98. Bristles 98 extend along an axis 100, that can beperpendicular from the forward end of head member 92 and from fourthaxis 86 as shown. Alternately, bristles 98 can extend along an axis thatis at some other angle from the forward end of head member 92 and fromaxis 86. In use, brush head 96 reciprocates through angular sweep A₂ atan average angular speed W₂, about fourth axis 86. Angular sweep A₂ isdifferent than angular sweep A₁ and in the embodiment shown, angularsweep A₂ is larger than angular sweep A₁. Similarly, the average angularspeed W₂ is different than, and in the embodiment shown, larger than theaverage angular speed W₁. The sweeping action of the brush head member92 along angular sweep A₂ and at average angular speed W₂ simulates theback-and-forth brushing action that occurs when a person brushes theirteeth with a manual toothbrush. Brush head member 92 is removable forreplacement when brush head 96 becomes worn or broken.

[0020] First member 30, second member 54, and third member 60, notincluding gear member 76, make up a first transmission, shown generallyat 102. Transmission 102 transfers rotational motion about axis 28, fromoutput shaft 24 of motor 12 into rotational reciprocating motion ofslotted arm 72 through angular sweep A₁ at average angular speed W₁.Member 60, not including gear member 76 is the output member for thefirst transmission 102. Thus axis 68 is the output member axis for thefirst transmission 102.

[0021] Gear members 76 and 88 make up a second transmission, showngenerally at 104. Transmission 104 transfers the rotationalreciprocating motion of slotted arm 72 into rotational reciprocatingmotion of output member 20 through angular sweep A₂ at average angularspeed W₂, about axis 86. Member 88 is the output member for the secondtransmission 104. Thus axis 86 is the output member axis for the secondtransmission 104.

[0022] Reference is now made to FIG. 3, which shows drive mechanism 18assembled. It will be noted that axes 28, 34, 68 and 86 are allparallel. This is useful in that all of the components of drivemechanism 18 occupy a relatively small volume, so that they can fit in ahousing that is easy to grasp and hold in a user's hand.

[0023] In an alternative embodiment transmission 102 can be any suitablemeans for transferring rotational motion into rotational reciprocatingmotion, and particularly rotational reciprocating motion about an axisparallel to that of the motor output shaft.

[0024] In an alternative embodiment, the second transmission 104 can beany suitable means for changing the angular sweep of reciprocation andthe average angular speed of reciprocation.

[0025] As shown, brush head 96 can have a circular arrangement ofbristles 98. Alternatively, however, the brush head can have anysuitable arrangement of bristles.

[0026] As will be apparent to persons skilled in the art, variousmodifications and adaptations of the device described above arecontemplated without departure from the present invention.

1. An electric toothbrush, comprising: a housing; an electric motorconnected to said housing, said electric motor having a motor outputmember for rotation about a motor output axis; a first transmissionlinked to said motor output member, said first transmission to convertrotational movement from said motor output member into rotationalreciprocating movement at a first average angular speed; and a secondtransmission linked to said first transmission, said second transmissionto convert rotational reciprocating movement from said firsttransmission into rotational reciprocating movement at a second averageangular speed about a second transmission output axis that is parallelto said motor output axis and to drive an output member to reciprocateat said second average angular speed about said second transmissionoutput axis.
 2. An electric toothbrush as claimed in claim 1, whereinsaid second transmission comprises a first gear member, said first gearmember comprising a section of an internal gear connected to said firsttransmission, and a second gear member drivenly connected to said firstgear member, said second gear member comprises a spur gear.
 3. Theelectric toothbrush as claimed in claim 1, wherein said motor outputmember comprises a first gear, and said first transmission comprises: arotatable second gear member which mates with said first gear member; anorbiting member attached to said second gear, to convert rotation ofsaid second gear to orbital movement; and a rotatable slotted memberslidably connected to said orbiting member, to convert said orbitalmovement into rotational reciprocating movement at said first averageangular speed.
 4. The electric toothbrush as claimed in claim 1, whereinsaid output member comprises a brush head having an axis that is angledrelative to said second transmission output axis.
 5. The electrictoothbrush as claimed in claim 1, wherein said second average angularspeed is greater than said first average angular speed.
 6. An electrictoothbrush, comprising: a housing; an electric motor connected to saidhousing, said electric motor having a motor output member for rotationabout a motor output axis; a first transmission linked to said motoroutput member, to convert rotational movement from said motor outputmember into rotational reciprocating movement along a first angularsweep; and a second transmission linked to said first transmission, saidsecond transmission to convert rotational reciprocating movement fromsaid first transmission into rotational reciprocating movement along asecond angular sweep about a second transmission output axis that isparallel to said motor output axis and to drive an output member toreciprocate through said second angular sweep about said secondtransmission output axis.
 7. The electric toothbrush as claimed in claim6, wherein said output member comprises a brush head having an axis thatis angled relative to said second transmission output axis.
 8. Theelectric toothbrush as claimed in claim 6, wherein said second angularsweep is greater than said first angular sweep.
 9. An electrictoothbrush, comprising: a housing; an electric motor connected to saidhousing, said electric motor having a motor output member for rotationabout a motor output axis; a transmission linked to said motor outputmember, to convert rotational movement from said motor output memberinto rotational reciprocating movement along a first angular sweep; asection of an internal gear, said section connected to saidtransmission, for rotational reciprocating movement at said firstaverage angular sweep; and a gear drivenly connected to said section forrotational reciprocating movement along a second angular sweep about agear member axis that is parallel to said motor output axis and to drivean output member to reciprocate at said second average angular sweepabout said gear member axis.
 10. The electric toothbrush as claimed inclaim 9, wherein said output member comprises a brush head having anaxis that is angled relative to said gear member axis.